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Regional Connector Tunnel Boring Machine (TBM)

Meet Angeli. She’s connecting LA County.

“Angeli” is the name given to the Regional Connector Tunnel Boring Machine (TBM). She will dig twin 1.1 mile underground light-rail tunnels that connect the Metro Blue, Expo and Gold Lines allowing passengers to travel seamlessly about LA County from Long Beach to Azusa and East Los Angeles to Santa Monica. The tunnels will connect three new stations from Little Tokyo to the Financial District in downtown Los Angeles: the 1 st /Central Station in Little Tokyo, the 2 nd /Broadway Station in the Civic Center and 2 nd Pl/Hope St Station in Bunker Hill.

Why is she named?

Like ships, TBMs are named before they begin work for the first time—a mining tradition that dates back to the 14 th century. A female name is chosen because, historically, underground workers revered Saint Barbara—the patron saint for military engineers and miners—as a symbol of protection and good luck for centuries. This homage evolved into the tradition of naming tunneling machines with a female name before the digging begins.

In Spring 2016, Metro launched a naming and art contest and visited downtown area schools to educate students about this modern marvel. Over 300 students submitted original essays and illustrations that were evaluated by a judging panel led by community members. In Summer 2016, the public voted to choose the name and art work to be displayed on the side of the TBM. Windsor McInerny, freshman at Woodrow Wilson Classical High School, won the naming contest with her submission, “Angeli.” Alexander Li, senior at Camarillo High School, won the art contest.  His artwork is currently displayed on the TBM.

“Angeli” is Latin for the word “angels” and shares the name given to the city of Los Angeles, the City of Angels. “Angeli” represents the angel needed to complete this important project that greatly improves Los Angeles transportation. Read the full story about “Angeli” .

How does it work?

A TBM is like a giant drill. The TBM will slowly drill through the earth, digging the tunnels needed for the trains to travel underground. The front section of the TBM is called the shield. At the front of the shield is the cutter head. The cutter head is like a giant circular cheese grater. The shield has two jobs; it drills through the dirt to create a large hole which it then lines with concrete segments to form complete rings. These rings support the tunnel.

When will she start work?

“Angeli” starts work in early 2017, after she has been assembled and tested this fall. It will take approximately three months to put “Angeli” together. She will dig a tunnel starting from 1 st and Alameda in Little Tokyo to 4 th and Flower in the Financial District in downtown Los Angeles. It takes approximately 5 to 6 months to build one tunnel. Then she will return to Little Tokyo and dig a second tunnel to the Financial District.


Tunnel mining in Downtown Los Angeles

The Regional Connector Transit Project will construct two parallel tunnels to create seamless transit connections of the Expo, Gold, and Blue Lines. The new 1.9 mile railway will be constructed using a combination of tunnel boring machine and an “open-cut” method. Angeli will be responsible for 1.1 miles of tunneling, as she travels westerly from Little Tokyo to the Financial District. Each tunnel will take approximately six months to complete.

Learn more about tunneling

Along the way, Angeli will encounter different soil conditions. Progress is measured in total feet traveled and the number of rings she builds. Follow Angeli on Twitter for weekly updates on her progress and more.

Current Location: Zone 1 – Central Av to San Pedro St

Angeli is tunneling through the sand and gravel deposited by the ancient Los Angeles river for the first portion of her journey. Because the machine is shallow, grouting has been done in order to hold the ground in place.

Zone 1 – From Central Av to San Pedro St

Angeli will be tunneling through the sand and gravel deposited by the ancient Los Angeles river for the first portion of her journey. Because the machine is shallow, grouting has been done in order to hold the ground in place.

Zone 2 – From San Pedro St to Broadway

Angeli is tunneling slightly downhill through the Fernando bedrock formation, which is a soft rock that is very much like hard clay. She will be tunneling through the future Station under 2nd Street between Spring St and Broadway St, which will be excavated later in the project.

Zone 3 – From Broadway to Hope St

Angeli is tunneling uphill through Bunker Hill under the Red Line and then under the 2nd Street tunnels. Tunneling will continue to be in the Fernando bedrock formation, which is a soft rock that is very much like hard clay.

Zone 4 – From Hope St to 4th St

Angeli will take a left turn at the future Station near Hope and 3rd Street and will tunnel under Flower street to the end of her journey at 4th St. The ground in this section is mostly the Fernando bedrock formation, there will be sand and gravel deposits however near the top of the tunnel.

Overall Statistics

Zone Total Feet to Tunnel Rings to Build
Central Av to San Pedro St 790 158
San Pedro St to Broadway 1985 397
Broadway to Hope 1670 334
Hope to 4th St 1050 210
Total 5820 feet per tunnel 1099 rings per tunnel

Local area students recognized by Regional Connector Project Management at student award luncheon.

Local area students recognized by Regional Connector Project Management at student award luncheon.

Thank you to the over 300 students that entered the TBM Naming & Art Contest. For the naming contest, students submitted original essays that best explained the significance of their proposed name and its importance to the community. For the art contest, students submitted original illustrations that envisioned their ideal communities incorporating the new Regional Connector Line. The public cast their votes for the contest winners in Summer 2016.

Student contest winners were honored by Metro and local elected officials at the Regional Connector TBM Milestone Lowering Ceremony held on October 19, 2016. Students were awarded with Metro TAP card fare sponsored by Regional Connector Constructors .

TBM Art Contest Winners

TBM Naming Contest Winners

1 st Place: Alexander Li

12 th Grade, Adolfo Camarillo High School

1st Place: Alexander Li

2 nd Place: Siena Morgan

4 th Grade, The Waverly School

2nd Place: Siena Morgan

3 rd Place: Marlah Adviento

12 th Grade, Orthopaedic Hospital Medical Magnet High School

3rd Place: Marlah Adviento

1 st Place: Angeli

Windsor McInerny, 9 th Grade, Woodrow Wilson Classical High School

“Angeli” is the name I believe should be given to the Tunnel Boring Machine that will bore the tunnels for the Los Angeles Regional Connector and further Los Angeles and its growing transportation system. Angeli comes from the lost but ever so beautiful and strong language, Latin, and translated it means “angels.” As in, you’ve guessed it, the City of Angels, the same name given to our city, Los Angeles, by its founders. Because, if there is anything this city is, it is proud. The machine that will help connect Little Tokyo to the Financial District deserves a strong name, but also one that reflects us Los Angeles citizens - angels.

The Tunnel Boring Machine deserves a name that celebrates its purpose and welcomes it with open arms, to our great city. With all the Tunnel Boring Machine will do for us, let us welcome it as Angeli- the angel L.A. needs for this very difficult, but very important job that will improve our city’s transportation so much.

2 nd Place: Toph

Michelle Wong, 9 th Grade, Academia Avance Charter School

Hi! For my naming entry I decided to enter a name after a fictional character. That name would be, Toph. The name comes from the show Avatar: The Last Airbender . Toph in the show is a blind, earthbending girls that becomes one of the main characters in the show. First of all, Toph is an earthbender who hast the ability to move parts of the earth around while the TBM moves dirt around to hollow out a space. But honestly that young little girl is quite something when it comes to her intentions. The show portrayed her as a smart girl who learned to things differently with her sight gone. She taught the audience that the approval of others isn’t and will never be of her concern, because she knows who she truly is. Her true strength was hidden behind the false dainty image she set up. That’s my pick. I guess I’d end this little essay with a goodbye. Bye.

3 rd Place: Fortuna (Fortuna Redux)

John Marco Abaday, 11 th Grade, Edward Roybal Learning Center

I chose the name “Fortuna Redux” a Roman goddess who watches over all travelers. Travelers could look up to her for luck and safe trip. You can petition her for a happier, and luckier trip on the new Metro railway. She’s a goddess to look up to for good fortune within your journey.  She can also be petitioned for predictions about what is to come to your travels. Most people believe in luck or lucky charms. She could be someone to look up to for this. No matter what mode of travel you can ask for her blessings by carrying chamomile on your purse or putting an oak leaf on your shoe. She made a huge impact in Western Empire in 19 BC when she was introduced. People looked up to her for the safe return of soldiers, travelers and the Emperor.


Regional Connector Tunnel Boring Machine Milestone Lowering Ceremony

Oct. 19, 2016, in Little Tokyo in DTLA at future 1st/Central Station.


Please use the materials below to learn more about the Regional Connector Tunnel Boring Machine (TBM).


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